1. Field of the Invention
The present invention relates to a semiconductor device using a fluorinated silicate glass film as an interlayer metal dielectric film, and relates to a method of manufacturing a semiconductor device. More particularly, the present invention relates to an improvement in the adhesion between the fluorinated silicate glass film and a silicon nitride film serving as a protective insulation film.
2. Description of the Background Art
In a semiconductor device having a multilayer metal interconnection (a plurality of metal wire layers), a fluorinated silicate glass film (hereinafter simply called xe2x80x9cFSGxe2x80x9d) is used as an electrical insulation layer (hereinafter called an interlayer metal dielectric film (IMD)) to be interposed between the plurality of metal wire layers.
FIGS. 5A and 5B are cross-sectional views for describing a conventional semiconductor device.
In FIG. 5A, reference numerals 21 and 22 designate metal wire layers; 3 designates FSG serving as an interlayer metal dielectric film formed between the metal wire layers 21 and 22; and 5 designates a silicon nitride film which serves as a protective insulation film (also called a xe2x80x9cpassivation filmxe2x80x9d) and is to be laid on the highest layer of the semiconductor device.
In the conventional semiconductor device, the FSG serving as the interlayer metal dielectric film 3 emits free fluorine (not shown). The thus-emitted free fluorine diffuses outward, thus forming fluorine substances. The expression xe2x80x9cfluorine substancesxe2x80x9d used herein designates fluorine itself, contamination precursor components, and fluorine-containing contamination compounds spontaneously generated from the precursor components.
The fluorine substances are accumulated along a boundary surface between the FSG 3 and the silicon nitride film (serving as the protective insulation film) 5.
The silicon nitride film 5 has a strong blocking effect against the fluorine substances, thus preventing diffusion of the fluorine substances. Accordingly, the fluorine substances are accumulated at high concentration along a boundary surface between the FSG 3 and the silicon nitride film 5.
For this reason, there is a chance of swelling or exfoliation of the silicon nitride film 5 arising.
As shown in FIG. 5B, even in the vicinity of the outer periphery of a semiconductor substrate 1, the fluorine substances are concentrated along the boundary surface of the FSG 3 and the silicon nitride film 5. Therefore, the silicon nitride film 5 is prone to be exfoliated.
As mentioned above, weak adhesion exists between the FSG 3 serving as the interlayer metal dielectric film and the silicon nitride film 5 serving as the protective insulation film. Therefore, swelling or exfoliation of the silicon nitride film 5 arises, thereby deteriorating the performance or reliability of the semiconductor device.
The present invention has been conceived to solve the previously-mentioned problems and a general object of the present invention is to provide a novel and useful semiconductor device, and to provide a novel and useful method of manufacturing a semiconductor device.
A more specific object of the present invention is to improve adhesion between an interlayer metal dielectric film and a protective insulation film.
A more specific another object of the present invention is to prevent exfoliation of a protective insulation film from the vicinity of outer periphery of a semiconductor substrate.
The above objects of the present invention are attained by a following semiconductor device, and by a following method of manufacturing a semiconductor device.
According to one aspect of the present invention, the semiconductor device comprises a semiconductor substrate; a plurality of metal wire layers formed on the semiconductor substrate, a plurality of fluorinated silicate glass films formed respectively between the plurality of metal wire layers, and the plurality of fluorinated silicate glass films acting as interlayer metal dielectric film; a silicon nitride film formed on the highest fluorinated silicate glass film, and the silicon nitride film acting as a protective insulation film; and an adhesive layer formed between the highest fluorinated silicate glass film and the silicon nitride film.
In the semiconductor device, since the adhesive layer is formed between the highest fluorinated silicate glass film and the silicon nitride film, adhesion between the fluorinated silicate glass film and the silicon nitride film can be improved. Accordingly, swelling or exfoliation of the silicon nitride film can be prevented, which in turn improves the reliability of the semiconductor device.
According to another aspect of the present invention, the semiconductor device comprises a semiconductor substrate; a plurality of metal wire layers formed on the semiconductor substrate; a plurality of fluorinated silicate glass film formed between the plurality of metal wire layers, and the plurality of fluorinated silicate glass films acting as an interlayer metal dielectric film; and a silicon nitride film which is integrally formed on the sides of the highest fluorinated silicate glass film, on the highest fluorinated silicate glass film, and on the highest metal wire layer, and on the silicon nitride film acting as a protective insulation film.
In the semiconductor device, since the silicon nitride film is formed on the sides of the fluorinated silicate glass film as well, exfoliation of the silicon nitride film can be prevented from the edge of the fluorinated silicate glass film.
According to another aspect of the present invention, in a manufacturing method of a semiconductor device, a first metal wire layer is formed on a semiconductor substrate in a first metal wire layer formation step. Next, a fluorinated silicate glass film serving as an interlayer metal dielectric film is formed on the first metal wire layer in an interlayer metal dielectric film formation step. Next, a second metal wire layer is formed on the fluorinated silicate glass film in a second metal wire layer formation step. Next, an adhesive layer is formed on the fluorinated silicate glass film and on the second metal wire layer in an adhesive layer formation step. Next, a silicon nitride film serving as a protective insulation film is formed on the adhesive layer in a protective insulation film formation step.
In the semiconductor device, since the adhesive layer is formed between the fluorinated silicate glass film and the silicon nitride film, swelling or exfoliation of the silicon nitride film can be prevented.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.